Review Question - QID 109781

A 70-year-old man presents to the emergency department with resting dyspnea for the past 2 hours. His medical history is significant for asthma and chronic obstructive pulmonary disease. Despite albuterol, ipratropium, magnesium, methylprednisolone, and oxygen via high-flow nasal cannula, the patient agrees to elective intubation and is transferred to the intensive care unit. His hospital course is prolonged by pneumonia, which is managed with vancomycin, piperacillin-tazobactam, and gentamicin to cover for ventilator-associated etiologies. He is maintained on nasogastric tube feeds, lactated ringer fluid boluses, and subcutaneous heparin for deep vein thrombosis prophylaxis. On hospital day 7, the patient proves difficult to wean from his ventilator due to labored tachypnea. As the nurse rotates the patient to change his sacral pressure ulcer dressing, the patient's peak airway pressure increases sharply to 55 cm H2O. The nurse noted that the patient was wincing at the time. His temperature is 100.1°F (38.1°C), blood pressure is 100/50 mmHg, and pulse is 100/min. His respirations are 22/min on the ventilator despite a set respiratory rate of 14/min. His laboratory results are shown below:

Leukocyte count and differential:
Leukocyte count: 18,000/mm^3
Segmented neutrophils: 90%
Bands: 10%
Eosinophils: 5%
Basophils: 2%
Lymphocytes: 2%
Monocytes: 1%

Serum:
Na+: 135 mEq/L
Cl-: 107 mEq/L
K+: 3.2 mEq/L
HCO3-: 18 mEq/L
Urea nitrogen: 45 mg/dL
Glucose: 89 mg/dL
Creatinine: 1.3 mg/dL
Alkaline phosphatase: 100 U/L
Aspartate aminotransferase (AST, GOT): 250 U/L
Alanine aminotransferase (ALT, GPT): 300 U/L
Gamma-Glutamyltransferase (GGT): 2 U/L
Amylase: 10 IU/dL
Lipase: 5 IU/dL

Bedside ultrasound imaging is shown in Figure A. What is the most likely diagnosis?